Recent federal and state laws have mandated that all industrial waste pipelines must be replaced with dual-containment pipe or that a leak detection system must be installed and activated on each line section. Insofar as there is no cost-effective leak detection system that can be implemented for an existing single-containment pipeline, the only solution is to install a dual-containment pipeline. A dual-containment pipeline consists of an outer pipe and an inner pipe having a diameter less than the outer pipeline. The outer pipe may be made of any conventional piping (i.e. clay, plastic, concrete or metal). When inserted, the inner pipe must be centered within the host pipe so that equal annular space remains between the two pipes. This allows any flow outside of the inner pipe to be detected immediately.
Replacing existing single-containment pipelines with dual-containment pipelines would be overly burdensome. The cost of excavation alone in most industrial areas is excessive due to the contaminated soil surrounding the existing pipelines. Further, it is desirable to minimize destruction of surface features so not to disturb local residences, businesses and utilities. Therefore, a no dig solution for rehabilitating existing pipelines or converting existing single-containment pipelines with a dual-containment system would be beneficial.
It is known in the prior art to line existing pipelines with deformed inner pipelines for repair or restoration in situ. However, these methods provide an inner lining pipe that, when installed, fits snugly within the existing host pipe leaving no space between the two pipes. Tight-fitting pipe lining inserts are conventionally used to enhance the strength of the pipelines. These conventional methods of lining a pipeline include the steps of deforming flexible piping or tubing (e.g. polyethylene) to form a temporary fold therein, holding the tube in its deformed state, inserting the deformed tube into existing pipelines and releasing the tube so that it returns to its original cylindrical form. As representative of such art, reference may be had to U.S. Pat. No. 3,894,328 to Jansson.
In conventional methods, inner lining pipes were produced, deformed and wrapped in coils at the extrusion plants. This process created problems in quality control and increased cost due to excessive freight charges to ship the deformed lining pipe to the site of the pipe requiring the lining. Deforming the pipe away from the lining site also limited the size and the length of the polyethylene pipe that was to be deformed. Short length lining pipes require mechanical joints to fuse the pipes together, resulting in exfiltration of pollutants and chemicals into the surrounding groundwater aquifer. Therefore, the need arose to be able to deform straight cylindrical lengths of polymeric pipe on the actual job site. The prior art also shows deforming lining pipes at the site of a host pipe for insertion therein. However, the art has not provided a portable apparatus suitable for deforming polymeric pipe at the site of a host pipeline without using electrical power.
For example, U.S. Pat. No. 5,091,137 to Ledoux discloses deforming a thermoplastic extrudate (i.e. a lining pipe) into a U-shape to facilitate insertion into the pipe to be lined. In FIG. 1 of the patent, the deforming apparatus comprises a pair of fixed positioning rollers 14 and 16 located perpendicular to one another and a pair of adjustable positioning rollers 18 and 20 also located perpendicular to one another, and opposite rollers 14 and 16. The thermoplastic extrudate is deformed by applying heat and passing it through a motor-driven deforming or penetration wheel. When fully inserted, the lining pipe is pressurized and heated to return the pipe to its original round shape.
U.S. Pat. No. 4,207,130 to Barber shows a method of lining pipes including the steps of extruding the lining pipe on site, deflecting the pipe, holding the pipe in its deflected state, feeding the deflected pipe into a host pipe and releasing the hold on the pipe so that it returns to its original form. The deforming apparatus disclosed in FIG. 1 has a deflecting roller 16 carried by a frame 18 and folding rollers 20. A plastic extrudate 12 passes through a cold water spray 14 to set the plastic material. The deflecting roller then deflects the upper central portion of the tube so that it takes up a horseshoe type configuration and rollers 20 press the sides of the horseshoe cross section together. The lining pipe is propelled through the forming apparatus by driving roller 22 driven by motor 34.
Another approach of the art is exemplified by U.S. Pat. Nos. 5,114,634 and 5,256,342 to McMillan et al. which show reducing the diameter of a lining for insertion into a host pipe by passing an elastomeric liner pipe through five sets of rollers. In FIG. 2 of each patent, it is shown that each of the five sets of rollers define a 360 degree region of contact with the liner and that each set of rollers provides a progressively smaller liner-receiving opening to reduce the diameter of the lining pipe.